1. Field of the Invention
The present invention relates to fixing apparatuses that are mounted in image forming apparatuses and the like such as electrophotographic copiers, printers, facsimiles, and their complex machines, and specifically to fixing apparatuses provided with a cooling mechanism that cools fixed paper sheets on a paper transport guide.
2. Description of the Related Art
In image forming apparatuses such as copiers and printers, high-speed operation along with high-quality image formation have been sought, but a given amount of heat is needed in order to have toner fixed to paper sheets. Moreover, cooling of paper sheets after fixing is not sufficiently performed with high-speed operation, and thus a toner blocking phenomenon will occur in which toner on one paper sheet sticks to another paper sheet loaded on a discharge tray.
Moreover, in duplex printing, hot paper sheets of which one side has been fixed are transported again to a photosensitive drum. When this duplex printing is used often, a temperature increase of the photosensitive drum is caused, and the life of the photosensitive drum may be shortened and poor cleaning and the like may be caused.
Some image forming apparatuses of this kind cool paper sheets which have been heated at the time of fixing. A method for cooling paper sheets after fixing is disclosed in which air vents are provided in a paper transport guide and air flow is formed to cool output paper sheets (for example, JP 2006-349755A, JP 2009-192998A, and JP 2010-30749A).
Moreover, some image forming apparatuses are disclosed in which solenoids are provided in a fixing apparatus as a separation claw driving means that makes a paper separation claw come into contact with and separate from the surface of a fixing roller and a pressure roller in order to reliably prevent occurrence of paper clogging (jam) at a fixing portion when paper sheets are wound around the fixing roller and the pressure roller of the fixing apparatus (for example, JP 2008-225223A, JP 2001-242738A, and JP 2007-225780A).
The solenoid serving as a drive source for separation/contact operations of a paper separation claw is required to ensure stable and long-time separation/contact operations of the paper separation claw even if the solenoid is incorporated in the fixing apparatus and used in a high temperature environment. Moreover, since the solenoid itself is an electric component and serves as a heat generating source, the solenoid is required to be cooled appropriately.
However, since paper sheets that retain unfixed toner images pass through the fixing apparatus, it is difficult to employ a method in which cooling air generated by a cooling fan is guided into the fixing apparatus via a ventilation channel and is blown directly to the heat generating source to cool it. Therefore, conventionally, a method is often employed in which heat generated at heat generating sources such as the fixing apparatus and other components is sucked by suction fans provided on the apparatus casing of an image forming apparatus through a suction duct, and is discharged to the outside of the apparatus to cool each portion of the inside of the image forming apparatus.